Arthritis in psoriasis.

A group of 61 unselected patients with psoriasis attending a dermatology clinic were studied to determine the prevalence of psoriatic arthritis. On defined criteria arthritis was present in 41.6%. Peripheral arthritis was present in 15.5%, and sacroiliitis in 43%. A strong association of distal interphalangeal arthritis with psoriasis and nail dystrophy was confirmed. Tissue typing showed a strong association of B23, 17, in Caucasoid psoriatics, while the haplotype A1/B8 was increased in mixed Caucasoid--Negroid psoriatics.